Wiji

- add better error messages : https://github.com/komuw/wiji/pull/54
- Stop capturing `SIGINT` signal : https://github.com/komuw/wiji/pull/55

- rename CLI option, `--config` to `--app` : https://github.com/komuw/wiji/pull/52

- bugfix, `task.task_options is stale`
We had a case where `broker.done` would get called with `task_id`==`''`(empty string) : https://github.com/komuw/wiji/pull/39
- add timestamp to log events: https://github.com/komuw/wiji/pull/45
- remove `wiji.task.WijiRetryError`.
we replace it with a `wiji.task.Task._RETRYING` boolean.: https://github.com/komuw/wiji/pull/46
- rename wiji conf file: https://github.com/komuw/wiji/pull/47
- `wiji` no longer requires task instances in order to start running : https://github.com/komuw/wiji/pull/49

- fix examples broker which was broken by last PR: https://github.com/komuw/wiji/pull/35

- `wiji.broker.BaseBroker` interface should have a method that is called during shutdown
and `wiji.Worker` calls this method when it receives a shutdown signal like `SIGTERM`: https://github.com/komuw/wiji/pull/34

- all task invocations should have unique task_id: https://github.com/komuw/wiji/pull/32